There is a strong incentive to reduce vehicle emissions in the automotive industry. Traditionally, this has been done by improving fuel efficiency of combustion engines, reducing aerodynamic drag, reducing rolling resistance of vehicle tires, etc. In recent years, hybrid electric vehicles, at least partially being propelled by electric motors, as well as purely electrically propelled vehicles have found their way to market. The CO2 emissions of such vehicles are substantial lower than the CO2 emissions of vehicles solely being propelled by combustion engines. Also, hybrid electric vehicles and purely electrically propelled vehicles have the advantage of being able to store energy being produced during braking. Especially during city driving which is associated with a plurality of start and stop events, such energy storage has the potential of a significant reduction of CO2 emissions. Even though hybrid electric vehicles and purely electrically propelled vehicles have advantages over traditional vehicles solely being propelled by combustion engines, they do have some drawbacks. Such a drawback is the accommodation of a bulky and heavy battery pack. For example, a battery pack of a purely electrically propelled vehicle can weigh as much as 450 kg. The weight of such a battery pack reduces the total energy efficiency of the vehicle, as well as the performance of the vehicle, both with regard to acceleration and cornering abilities. Further, such a battery pack requires a considerable amount of space inside the vehicle why areas such as the luggage compartment have to be adapted and reduced to accommodate the battery pack. In addition, such a battery pack requires a considerable amount of cooling during use. Therefore, battery packs of hybrid electric vehicles and purely electrically propelled vehicles are often provided with cooling systems such as fans, air-ducts and cooling boxes. Also, since overheating a battery pack is potentially dangerous, such a cooling system often has some sort of temperature monitoring and feedback system.
Attempts have been made to adapt existing vehicle parts such that these can be used to store electric energy. A rechargeable battery which is incorporated into a structural component is described in the document WO 2011098794 A1. Such component could be used as an energy storing unit which would overcome some of the above described drawbacks of battery packs. However, since the rechargeable battery described in the document is a capacitor type battery it has a low energy storage capacity and thereby has a limited potential to replace the battery pack of a hybrid electric or purely electrically propelled vehicle.
Therefore, in view of the above mentioned drawbacks with the prior art solutions, there is a need for a vehicle component which could be used as an energy storing unit with high energy storing potential.